Although the animals could swim back into the loch, there was currently no sign of the whales there, the group said.

Dave Jarvis, from the BDMLR, said: "Medics on the scene at Loch Carnan, South Uist, are reporting that the pod of pilot whales has now moved from the location they were in earlier and appear to be endeavouring to leave and head south, but hugging the coastline.

"The Scottish government has offered the use of fisheries protection vessel Hirta to shadow the animals' movements and this offer has been accepted. The boat is expected in the area within the next few hours."

But he said the pod were not yet in the clear.

"The remainder of the coastline is predominantly rocky with numerous inlets and bays which present a separate set of dangers to the creatures."

Some of the whales have injuries to their heads, thought to have been sustained when they struck the rocky shoreline of the loch.

The BDMLR dispatched nearly all its whale floatation devices from across the UK in case the mammals beached, and rescuers remain on standby with the inflatable pontoons to help float any stranded whales.

A pod of around 35 pilot whales was involved in a similar emergency at Loch Carnan, a small, narrow loch near the northeastern corner of the island, last October. After being watched closely by the BDMLR, the SSPCA and the coastguard, they went back to sea.

But less than a week later the same pod is believed to have been involved in a mass stranding in County Donegal in Ireland, when 33 pilot whales were found dead on a beach.

Pilot whales are among the most common cetaceans, and the adult male can grow to 20ft long.